Evidence for an anomalous quantum state of protons in nanoconfined water
| Autor: | P. M. Platzman, Stephen J. Paddison, Alexander I. Kolesnikov, Alexander P. Moravsky, George Reiter, J. Mayers, Mark A. Adams |
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| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | Physical Review B. 85 |
| ISSN: | 1550-235X 1098-0121 |
| DOI: | 10.1103/physrevb.85.045403 |
| Popis: | Deep inelastic neutron scattering provides a means of directly and accurately measuring the momentum distribution of protons in water, which is determined primarily by the proton ground-state wave function. We find that in water confined on scales of 20 \AA{}, this wave function responds to the details of the confinement, corresponds to a strongly anharmonic local potential, shows evidence in some cases of coherent delocalization in double wells, and involves changes in zero-point kinetic energy of the protons from $\ensuremath{-}$40 to +120 meV difference from that of bulk water at room temperature. This behavior appears to be a generic feature of nanoscale confinement. It is exhibited here in 16 \AA{} inner diameter carbon nanotubes, two different hydrated proton exchange membranes (PEMs), Nafion 1120 and Dow 858, and has been seen earlier in xerogel and 14 \AA{} diameter carbon nanotubes. The proton conductivity in the PEM samples correlates with the degree of coherent delocalization of the proton. |
| Databáze: | OpenAIRE |
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